This disclosure pertains to a linear tension member comprising multiple fibers which linear tension member floats in aqueous liquids.
Linear tension members are applied for many different purposes. In some circumstances, it is advantageous if the linear tension member can float in water. For example, ropes that are used in marine environments and fall accidentally into the water are easily seen, can be easily retrieved if they float and are prevented from contact with underwater elements, such as rotating parts.
Linear tension members made from materials with a higher density than water do not float but instead sink in water. Several fibers commonly used to produce linear tension members have a higher density than water, e.g. aramids have a density of ca. 1.4 g/cm3, polyester of ca. 1.4 g/cm3, polyamide of ca. 1.15 g/cm3.
Linear tension members made from these fibers do not float in water.
KR20120058837 describes a fiber, e.g., made from aramid, which can float in distilled water. The fiber is treated with a finish of silicone oil, which preferably comprises at least 99% of silicone oil.
However, silicone oil has several disadvantages when used. Silicone has a negative impact on adhesion or bonding with other material. The friction coefficient of silicone is low which hinders interconnection of fibers during manufacture, use and transport. A linear tension member coated with silicone can therefore only with difficulties be coated with another material. Also, silicone oil has a low biodegradability and is therefore less suited for application in marine environments. Another disadvantage of silicone is its high price.
U.S. Pat. No. 3,578,763 pertains to floatable cords for use in fishing nets and the like comprising a core of continuous filaments, a braided sleeve and particles of expanded plastic material between the sleeve and the core, e.g., polystyrene particles. The disadvantage of these cords is that the cord diameter is significantly increased by the expanded particles and the cord construction always requires a sleeve to hold the expanded particles in place. Also the manufacture of such cords is relatively complicated and requires multiple steps.